This study aims to determine whether cognitive behavior therapy is effective in reducing homesickness in internship doctor. This research uses single case experiment research design, where the model used is A-B-A. The study was conducted to one internship doctor who has been undergoing internship for four months at Karimun Hospital and feel homesick. The results showed that cognitive behavior therapy done to the subject is proven effective in reducing homesickness for the internship doctor at Karimun hospital. It is seen from the results of pre test questionnaire and post test and through daily emotional measurement.